Radiation Transfer Calculations and Assessment of Global Warming by CO2

We present detailed line-by-line radiation transfer calculations, which were performed under different atmospheric conditions for the most important greenhouse gases water vapor, carbon dioxide, methane, and ozone. Particularly cloud effects, surface temperature variations, and humidity changes as well as molecular lineshape effects are investigated to examine their specific influence on some basic climatologic parameters like the radiative forcing, the long wave absorptivity, and back-radiation as a function of an increasing CO2 concentration in the atmosphere. These calculations are used to assess the CO2 global warming by means of an advanced two-layer climate model and to disclose some larger discrepancies in calculating the climate sensitivity. Including solar and cloud effects as well as all relevant feedback processes our simulations give an equilibrium climate sensitivity of CS = 0.7°C (temperature increase at doubled CO2) and a solar sensitivity of SS = 0.17°C (at 0.1% increase of the total solar irradiance). Then CO2 contributes 40% and the Sun 60% to global warming over the last century.

Rainfall Variability and Trend Analysis of Annual Rainfall in North Africa

The IPCC climate models predict, for the Maghreb countries, lower rainfall and increased aridity. Current observations in the three countries of central Maghreb (Morocco, Algeria, and Tunisia) are not consistent with these predictions. To demonstrate this new trend, a detailed regional analysis of rainfall evolution is conducted. This investigation is based on the calculation of the reduced centered index and the chronological graphical method of processing information (MGCTI) of “Bertin matrix” type. The results show extreme variability of this parameter and the severe past drought (more intense for Morocco, in which the drastic conditions from the seventies are observed). The results also show the beginning of a gradual return to wetter conditions since the early 2000s in Algeria and Tunisia and from 2008 for Morocco (this trend is confirmed by recent agricultural production data in 2011/2012 and 2012/2013).

A Significant Population Signal in Iranian Temperature Records

We assembled daily maximum and minimum temperature records for 31 stations throughout Iran over the period 1961–2010. As with many other areas of the world, we found that both the maximum and minimum temperatures were increasing overall with the minimum temperatures increasing twice as fast as the maximum temperatures. We gathered population data for the stations near the beginning and end of the temperature records and found in all seasons and for both the maximum and minimum temperatures the magnitude of population growth positively influenced the temperature trends. However, unlike so many other studies, we found the strongest population growth signal in the winter for the maximum temperatures. We found evidence that this winter-season population-temperature signal is related snow cover. Our results illustrate that any number of processes are involved in explaining trends in historical maximum and minimum temperature records.

Detecting Warming Hiatus Periods in CMIP5 Climate Model Projections

The observed slow-down in the global-mean surface temperature (GST) warming from 1998 to 2012 has been called a “warming hiatus.” Certain climate models, operating under experiments which simulate warming by increasing radiative forcing, have been shown to reproduce periods which resemble the observed hiatus. The present study provides a comprehensive analysis of 38 CMIP5 climate models to provide further evidence that models produce warming hiatus periods during warming experiments. GST rates are simulated in each model for the 21st century using two experiments: a moderate warming scenario (RCP4.5) and high-end scenario (RCP8.5). Warming hiatus periods are identified in model simulations by detecting (1) ≥15-year periods lacking a statistically meaningful trend and (2) rapid changes in the GST rate which resemble the observed 1998–2012 hiatus. Under the RCP4.5 experiment, all tested models produce warming hiatus periods. However, once radiative forcing exceeds 5 W/m2—about 2°C GST increase—as simulated in the RCP8.5 experiment after 2050, nearly all models produce only positive warming trends. All models show evidence of rapid changes in the GST rate resembling the observed hiatus, showing that the climate variations associated with warming hiatus periods are still evident in the models, even under accelerated warming conditions.

Fire-Risk Assessment in Northern Greece Using a Modified Fosberg Fire-Weather Index That Includes Forest Coverage

The spatial distribution of the monthly mean values for various climatological parameters in Northern Greece is derived. The corresponding data come from measurements at several meteorological stations located in Central Macedonia, Eastern Macedonia, and Thrace (CM/EMT) area in the period 1975–1997. The collected data concern high temperature and low relative humidity, as well as local forest coverage, and are utilized for the calculation of a modified Fosberg Fire-Weather Index in order to estimate the fire risk over Northern Greece due to the local weather under critical conditions. As a result, monthly fire-risk maps of the CM/EMT area for the months of May to October are derived for the first time by applying sophisticated analytical geospatial tools and methods. Furthermore, fire events corresponding to the same region and period are added to the derived maps for comparison and for a better evaluation of the method. The resulting correspondence of the predicted fire risk to the local wind-speed behavior and forest abundance demonstrates the need of the necessary precaution measures to limit the future danger levels from fire events.

A Quantitative Assessment of Surface Urban Heat Islands Using Satellite Multitemporal Data over Abeokuta, Nigeria

The fast urban expansion has led to the transformation of the natural landscape into anthropogenic surfaces. The city of Abeokuta, for instance, is located in a region experiencing rapid urbanization, which has produced a remarkable effect on the surface thermal response. This effect significantly influences urban internal microclimatology on a regional scale. In this study, the surface temperatures and land cover types retrieved from Landsat TM and ETM+ images of Abeokuta city for 1984, 2003, and 2014 were analyzed. A quantitative approach was used to assess surface urban heat islands through the relationships among surface temperature and land cover types. Results showed that impervious surface areas were found to be correlated positively with high temperatures. Conversely, vegetated areas and bare surfaces correlated positively with mid temperature zones. This study found that areas with increasing impervious surfaces will accelerate LST rise and consequently lead to increasing effect of surface urban heat islands. These findings pose a major challenge to urban planners. However, the study would help to quantify the impacts of different scenarios (e.g., vegetation loss to accommodate urban growth) on LST and consequently to devise appropriate policy measures.

Chemical Characteristics of Rainwater in Sumatera, Indonesia, during 2001–2010

The chemical composition of acid deposition shows that ammonium and chloride concentrations as the indicators of forest fires were higher than sulfate and nitrate in Sumatera areas such as Medan, Lampung, Palembang, and Kototabang. Chloride had higher concentration than sodium (Na+ sea originated) with the ratio value of Cl−/Na+ > 1.16 found in Medan and Palembang. Ionic compositions from the lowest to the highest concentration in Kototabang were H+ > Cl− > Na+ > NH4+ > nss-Ca2+ > K+ > NO3- > nss-SO42- > Mg2+ > ss-SO42- > ss-Ca2+. Acid rain takes place if the acid compounds such as sulfates, nitrates, and chlorides dominate. If the ratio value of NO3-/(nss-SO42- + NO3-) < 0.5 then it indicates that nss-SO42- is higher than NO3-. Between 2001 and 2010 it was found that the frequency value of NO3-/(nss-SO42- + NO3-) < 0.5 was 97% from annual mean of 34 pieces of data in Medan, Kototabang, Lampung, and Palembang. Forest fires influence was more dominant than anthropogenic activities in Kototabang, Palembang and Lampung, except in Medan. It showed that ammonium was higher than NO3- content if the ratio value of NO3-/(NH4+ + NO3-) < 0.5 was 62%. For the period 2001–2010 the frequency value of NO3-/(NH4+ + NO3-) < 0.5 was 74% from total 34 annual mean pieces of data in four locations, that is, Medan, Kototabang, Palembang, and Lampung.

The Role of Kenya Meteorological Service in Weather Early Warning in Kenya

Early warning in weather forecasting entails provision of timely and effective weather information that allows individuals, organisations, or communities exposed to likely weather hazards to take action that avoids or reduces their exposure to risks. Various sectors have developed different ways to mitigate the effects of climate anomalies. The study reviews the existing monitoring and response structures, and communications flow channels of weather data at different levels, focusing on the role of Kenya Meteorological Service (KMS). The methodology employed was literature review of various documents. The study argues that early warning and weather information communication are essential elements for effective governance of weather risks through a well-developed warning system. At the end, the study recommends strengthening the existing structures with respect to weather monitoring, processing, and dissemination of weather products to end users.

Characteristics of Summer Precipitation around the Western Ghats and the Myanmar West Coast

Characteristics of summer (June–August) precipitation over two coastal mountain regions in South Asia (Western Ghats: WG and Myanmar West Coast: MWC) with a focus on topographic impact are analyzed using the 13-year (1998–2010) high spatial resolution (0.05° × 0.05°) version 6 data obtained from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR). A relationship between precipitation patterns and topography was observed in the coastal mountains. In both the WG and MWC, maximum rainfall along a tight line on the upwind side of the coastal mountains is primarily attributed to rain frequency. However, intense precipitation was observed over the offshore regions. Compared with the WG, deeper and large-scale precipitation systems develop over the MWC, producing more intense rainfall. It is suggested that insufficient humidity deters large-scale convection over the WG, and the atmosphere is sufficiently moist over the MWC.

Simulation of Severe Local Storm by Mesoscale Model MM5 and Validation Using Data from Different Platforms

During premonsoon season (March to May) convective developments in various forms are common phenomena over the Gangetic West Bengal, India. In the present work, simulation of wind squall on three different dates has been attempted with the help of mesoscale model MM5. The combination of various physical schemes in MM5 is taken as that found in a previous work done to simulate severe local storms over the Gangetic West Bengal. In the present study the model successfully simulates wind squall showing pressure rise, wind shift, wind surge, temperature drop, and heavy rainfall, in all cases. Convective cloud development and rainfall simulation by the model has been validated by the corresponding product from Doppler Weather Radar located at Kolkata and TRMM satellite product 3B42 (V6), respectively. It is found that the model is capable of capturing heavy rainfall pattern with up to three-hour time gap existing between simulation and observation of peak rainfall occurrence. In all simulations there is spatial as well as temporal shift from observation.